Technical Field
The present invention relates to cooling systems and, more particularly, to active control of two-phase cooling systems taking advantage of changing electrical properties between coolant phases.
Description of the Related Art
In typical air-cooling environments, a processor core generates heat which is conducted through a thermal interface material (TIM) to a heat-spreader, typically made of copper. The heat spreader is attached to an air heat sink through a second TIM layer, and the heat sink conducts heat to the room ambient environment. In data centers, the ambient temperature is typically around 25 degrees Celsius. The total thermal resistance for a typical air cooled server is approximately 0.24 C/W, which for a 250 W processor results in a 60 degree Celsius temperature gradient between the ambient temperature and the processor core. This would result in a core temperature of 85 degrees Celsius.
Liquid cooling systems, and two-phase cooling systems in particular, can lower the thermal resistance substantially, thereby reducing the junction temperature. This minimizes processor power consumption at a given computational throughput. Generally, single or two-phase heat transfer involving small cavity channels leads to a larger heat transfer surface per unit flow area near the heat source when compared with large channel or pool-boiling approaches. However, two-phase liquid cooling systems can experience difficulties as they may, for example, dry out under heavy computational loads.